The disclosure relates to a laser leveling tool with adaptive thermal control function.
Laser leveling tools are generally used in construction and other fields. A laser leveling tool may comprise one or more laser diodes for generating laser lines. Over the past couple of years, the cost of high power red laser diodes dropped steadily. Therefore, high power laser diodes were used to increase laser line visibility. At the same time, more and more laser diodes were used in a laser leveling tool to form more laser lines. Higher laser diode power and more laser diodes in a product increase the thermal load of the products.
With the advance of laser diode manufacturing technologies, green laser diodes of various output power became available recently. Due to the higher energy photons of green laser radiation, the bias voltage of green laser diode is also higher, in the range of 6.0 V to 8.0 V. This is about three times higher than the 640 nm red laser diodes which need about 2.5 V forward bias voltage. This higher bias voltage results in more waste heat production as well as more power consumption.
Therefore, the use of high power red laser diode or green laser diode reduces the operation temperature envelop of laser leveling products and shorten the battery life. The waste heat of laser diode becomes an issue when the ambient temperature of the tool is high.
Recently, many laser leveling product manufacturers started release products using green laser diodes. All these products operated the laser diode in fixed pulsed mode, at 50% duty cycle at frequencies ranging from 5 kHz to 10 KHz. Operate the laser diodes at 50% duty cycle will reduce the thermal loading by about 60% (assuming a 90% switch mode power supply efficiency) as well as extending the battery life. The disadvantage is that the laser line visibility is also reduced by 50%.